1. Field of the Invention
The present invention relates to an imaging apparatus, and, more particularly, to a method of reducing printing defects in an ink jet printer.
2. Description of the Related Art
A typical ink jet printer forms an image on a print media sheet by ejecting ink from a plurality of ink jetting nozzles of an ink jet printhead to form a pattern of ink dots on the print media sheet. Such an ink jet printer typically includes a reciprocating printhead carrier that transports one or more ink jet printheads across the print media sheet along a bi-directional scanning path defining a print zone of the printer. Typically, the mid-frame provides media support at or near the print zone. A sheet feeding mechanism is used to incrementally advance the print media sheet in a sheet feed direction, also commonly referred to as a sub-scan direction or vertical direction, through the print zone between scans in the main scan direction, or after all data intended to be printed with the print media sheet at a particular stationary position has been completed.
The reciprocating printhead carrier is supported, for example, by at least one guide rod. The printhead carrier includes a pair of axially spaced bearings having respective apertures for receiving the guide rod. One parameter that limits print quality in bi-directional printing is the carrier bearing clearance, i.e., the amount of clearance between the carrier bearings and the associated guide rod. Bearing clearance is necessary from a manufacturing tolerance perspective, and typically the tighter the tolerances the more expensive the printer. The effect of the bearing clearance is a shift in the registration position of the ink jet printhead with respect to a print area on the print media sheet. It has been observed that this shift occurs mainly in the vertical, i.e., print media advance, direction.
What is needed in the art is a method of reducing printing defects in an ink jet printer, such as for example, printing defects due to carrier bearing clearances.